COMPOSITE MANUFACTURING KYLE KINGHORN BRIGHAM YOUNG UNIVERSITY-IDAHO UAMMI-March 27, 2019  Composite Material: A material made from two or more constituent materials with significantly different material properties that, when combined, produce a material with characteristics different from the individual components WHAT IS A COMPOSITE?

 Composites consist of a reinforcement and a matrix  Egyptians found that straw mixed with clay made a stronger brick. The straw is the reinforcement, and the clay is the matrix.  Mongolian bows were made with animal sinew (reinforcement) glued to a wooden bow (matrix) COMPOSITE MAKEUP

 Matrix Materials  Polymer Polyester, Epoxy, Nylon  Ceramic Clay with straw reinforcement  Metal Metal Matrix Composites  Reinforcement  Polymer Kevlar, Spectra  Ceramic Glass, Carbon Fiber  Metal Steel in concrete

COMPOSITE MAKEUP

 Although many materials could be considered a composite (such as reinforced concrete, wood), the term composite generally refers to a structural fiber and a plastic--Fiber Reinforced Plastic (FRP)  Common fibers include  Fiberglass  Carbon Fiber  Aramid Fiber (Kevlar)  Basalt, Boron, Natural fibers (wood, flax, hemp, etc.)  Common plastic resins in composites . Reinforcement Type:  Epoxy . Particulates  Polyester . Whiskers (short fibers, 2mm or less)  Vinyl Ester . Fibers (2mm or longer)  Polyurethane  Polypropylene, Nylon, Polycarbonate, etc. THERMOPLASTIC COMPOSITES

 By volume, (80%) most composite manufacturing is done with THERMOPLASTIC materials  Small “whiskers” of particulates (usually glass) are placed in any type of thermoplastic material and injection molded  Advantages: Stronger, stiffer, more thermally stable materials  Disadvantages: More abrasive on equipment, more expensive, less flexibility Example: Glass Filled Nylon 6/6

THERMOPLASTIC COMPOSITES THERMOPLASTIC COMPOSITES

Glass-filled Polypropylene Glass-filled Nylon

Glass-filled Polycarbonate CONTINUOUS FIBER REINFORCED PLASTICS (CFRP)

 For Continuous Fiber Reinforced Plastics (CFRP), most employ a thermosetting matrix  Low viscosity of components prior to cure allow for good fiber wetout  Properties of thermosetting materials can be fine-tuned depending on application  Engineering Composites  Low cost matrix (Polyester) & low cost reinforcement (Fiberglass)  Short fiber length, Poor control of resin/fiber ratio  Advanced Composites  Better mechanical properties of matrix (epoxy) & reinforcement (Carbon)  Long fiber length, precise control of fiber placement and orientation  Precise control of resin/fiber ratio COMPOSITE PROCESSING TECHNIQUES

 Open Molding Processes  Wet lay-up (manual or chopper gun)  Pre-preg, vacuum bagging  Roll wrapping  Closed Molding Processes  RTM, VARTM  Bladder Molding  Compression Molding  Pultrusion  Filament Winding OPEN MOLDING-ENGINEERING COMPOSITES

 Chopper Gun  Short fibers (1”-2”) are sprayed on a with resin and catalyst  Any air pockets need to be removed and fibers fully wetted out, usually with rollers  Used for bathtubs, spas, railroad cars OPEN MOLDING-ENGINEERING COMPOSITES

 Hand Layup  Fiberglass fabric laid into mold  Catalyzed resin is spread over fabric  Fibers are wet-out with roller  Used routinely for boats and car parts OPEN MOLDING-ENGINEERING COMPOSITES OPEN MOLDING-ADVANCED COMPOSITES

 Pre-Pregs are generally used  Fibers pre-impregnated with resin, then B-staged prior to final cure  Once laid-up on mold, a vacuum is applied  Many aerospace parts are cured in an autoclave (high pressure oven) OPEN MOLDING-ADVANCED COMPOSITES

 Fiber Placement  Pre-preg material can also be cut and placed on open molds autonomously using 5 or 6-axis robots prior to vacuum bagging and autoclave

OPEN MOLDING-ADVANCED COMPOSITES OPEN MOLDING-ADVANCED COMPOSITES

 Roll wrapping  Pre-cut pre-preg material is rolled around a steel mandrel  Shrink tape is wrapped around the part  While curing, the shrink tape compacts the material against the mold  Once cured, the mandrel is pushed out  Great for tubes with constant cross-section OPEN MOLDING-ADVANCED COMPOSITES CLOSED MOLD PROCESSES-ADVANCED COMPOSITES

 Vacuum Infusion  Used extensively in making boat hulls  Dry fibers placed on single mold  Vacuum bag placed over fibers  Vacuum draws resin throughout  Part removed once cured  Advantages: Fewer VOCs emitted, ability to do large parts

CLOSED MOLD PROCESSES-ADVANCED COMPOSITES

 Resin Transfer Molding  BMW uses this process for the i3 and i8  Dry fibers placed in matched metal tool  Low viscosity resin pumped in under pressure (HP-RTM)  Part removed once part is cured  Advantages: Finished surface on both sides, fast cycle times  Disadvantages: Large up-front costs for equipment and tooling  A vacuum may be applied to help flow of material (VARTM) CLOSED MOLD PROCESSES-ADVANCED COMPOSITES CLOSED MOLD PROCESSES-ADVANCED COMPOSITES

 Bladder Molding  Widely used to create hollow carbon fiber parts that need to have a finished outer surface  Pre-cut pre-preg material is wrapped around inflatable mandrel (bladder)  Pressure is applied at temperature, forcing the material to conform to the shape of the tool  Once cured, the pressure is reduced and the part is extracted CLOSED MOLD PROCESSES-ADVANCED COMPOSITES CLOSED MOLD PROCESSES-ADVANCED COMPOSITES

 Compression Molding  Utilizes Bulk Molding Compounds (BMCs) and Sheet Molding Compounds (SMCs)  Molding compound is placed in a mold  The mold is compacted in a heated press (pressures up to 2000 psi)  Fast cycle times (1-5 minutes)  Ribs, bosses, and inserts can be molded in  Well suited for high-production volumes (i.e. auto industry) OTHER MANUFACTURING PROCESSES

 Pultrusion  In extrusion, material is pushed through a die  In pultrusion, the fibers are pulled through a resin bath, then through a heated die  Composite is fully cured upon exiting the die  Material is cut to length  High volume production of parts with constant cross-section OTHER MANUFACTURING PROCESSES OTHER MANUFACTURING PROCESSES

 Filament Winding  A fabrication technique mainly used for open (cylinders) or closed end structures (such as pressure vessels or tanks)  In a process similar to pultrusion, fibers are pulled through a resin bath and are wound under tension around a rotating mandrel  Tow-pregs may also be used  Useful in making SCUBA tanks, high pressure gas (HPG) tanks, missile casings, golf club shafts, etc.  Smart Mandrels may also be used for complex shapes OTHER MANUFACTURING PROCESSES WHERE ARE COMPOSITES HEADED?

 Why use composites?  High strength to weight  Ability to “sculpt” complex shapes, design for strength in different directions  Inherent properties of composites (corrosion resistance, fatigue life, appearance, etc.)  What is needed going forward?  Faster cycle times  Resin chemistry is constantly being tweaked to increase speed of production  Thermoplastic composites  Lower Cost  Carbon fiber is orders of magnitude more expensive that steel  “Out of Autoclave” production  Lower labor and tooling costs THANK YOU!

KYLE KINGHORN DEPARTMENT OF ENGINEERING TECHNOLOGY-BYU-IDAHO 525 S CENTER STREET AUS 159D REXBURG, ID 83440 [email protected]